In Vitro and in Vivo Pharmacological Characterization of the Neuropeptide S Receptor Antagonist [D-Cys(tBu)5]Neuropeptide S

Neuropeptide S (NPS) was identified as the endogenous ligand of an orphan receptor now referred to as the NPS receptor (NPSR). In the frame of a structure-activity study performed on NPS Gly5, the NPSR ligand [D-Cys(tBu)5]NPS was identified. [D-Cys(tBu)5]NPS up to 100 M did not stimulate calcium mo-bilization in human embryonic kidney (HEK) 293 cells stably expressing the mouse NPSR; however, in a concentration-dependent manner, the peptide inhibited the stimulatory effects elicited by 10 and 100 nM NPS (pKB, 6.62). In Schild analysis experiments [D-Cys(tBu)5]NPS (0.1–100 M) produced a con-centration-dependent and parallel rightward shift of the con-centration-response curve to NPS, showing a pA2 value of 6.44. Ten micromolar [D-Cys(tBu)5]NPS did not affect signaling at seven NPSR unrelated G-protein-coupled receptors. In th